1. Field of the Invention
The present invention relates to a pair of composite torque hinges especially suitable for use as an opening/closing device for opening/closing bodies such as seats, lids or the like of Western-styled lavatory stools.
2. Description of the Prior Art
As opening/closing devices for seats and lids of Western-styled lavatory stools, according to the prior art, what consists of a rotating shaft on which a cam mechanism having a compression spring is caused to act on, and what uses a torsion spring functioning in a direction to cancel the rotational torque working in a specific rotational direction of a rotating shaft are publicly known.
The known configuration consisting of a rotating shaft, on which a cam mechanism having a compression spring is caused to act, has the advantage that the created torque can be readily matched with the rotational moment of the seat or lid, but it also has the disadvantage that a large apparatus is needed to achieve a great rotational torque.
On the other hand, the known one which causes only a torsion spring to work on the rotation shaft, though having the advantage that a great rotational torque can be created even by a small mechanism, involves the disadvantage that it is difficult to match the rotational torque it creates, because it increases or decreases linearly, with the rotational moment of the seat or lid, which varies in a sine curve, and therefore to align details with the rotational moment of the seat or lid or to accentuate any part of the action thereof.